Statistical analysis rules out natural-warming hypothesis with more than 99 per cent certainty
An analysis of temperature data since 1500 all but rules out the possibility that global warming in the industrial era is just a natural fluctuation in the earth’s climate, according to a new study by McGill physics professor Shaun Lovejoy.
The study, published online on April 6, in the journal Climate Dynamics, represents a new approach to the question of whether global warming in the industrial era has been caused largely by man-made emissions from the burning of fossil fuels. Rather than using complex computer models to estimate the effects of greenhouse-gas emissions, Lovejoy examines historical data to assess the competing hypothesis: that warming over the past century is due to natural long-term variations in temperature.
“This study will be a blow to any remaining climate-change deniers,” Lovejoy says. “Their two most convincing arguments – that the warming is natural in origin, and that the computer models are wrong – are either directly contradicted by this analysis, or simply do not apply to it.”
Lovejoy’s study applies statistical methodology to determine the probability that global warming since 1880 is due to natural variability. His conclusion: the natural-warming hypothesis may be ruled out “with confidence levels great than 99 per cent, and most likely greater than 99.9 per cent.”
To assess the natural variability before much human interference, the new study uses “multi-proxy climate reconstructions” developed by scientists in recent years to estimate historical temperatures, as well as fluctuation-analysis techniques from nonlinear geophysics. The climate reconstructions take into account a variety of gauges found in nature, such as tree rings, ice cores, and lake sediments. And the fluctuation-analysis techniques make it possible to understand the temperature variations over wide ranges of time scales.
For the industrial era, Lovejoy’s analysis uses carbon-dioxide from the burning of fossil fuels as a proxy for all man-made climate influences – a simplification justified by the tight relationship between global economic activity and the emission of greenhouse gases and particulate pollution, he says. “This allows the new approach to implicitly include the cooling effects of particulate pollution that are still poorly quantified in computer models,” he adds.
While his new study makes no use of the huge computer models commonly used by scientists to estimate the magnitude of future climate change, Lovejoy’s findings effectively complement those of the International Panel on Climate Change (IPCC), he says. His study predicts, with 95 per cent confidence, that a doubling of carbon-dioxide levels in the atmosphere would cause the climate to warm by between 1.9 and 4.2 degrees Celsius. That range is more precise than – but in line with – the IPCC’s prediction that temperatures would rise by 1.5 to 4.5 degrees Celsius if CO2 concentrations double.
“We’ve had a fluctuation in average temperature that’s just huge since 1880 – on the order of about 0.9 degrees Celsius,” Lovejoy says. “This study shows that the odds of that being caused by natural fluctuations are less than one in a hundred and are likely to be less than one in a thousand.
“While the statistical rejection of a hypothesis can’t generally be used to conclude the truth of any specific alternative, in many cases – including this one – the rejection of one greatly enhances the credibility of the other.”
Read “Scaling fluctuation analysis and statistical hypothesis testing of anthropogenic warming”, S. Lovejoy, Climate Change, published online April 6, 2014.
So, if I understand this correctly – if it wasn’t for man made warming, we would still have the ice age glaciers and McGill University would be under five kilometers of ice.
Are we seriously still debating “global warming”? You scamicists have been proven to be nothing more than con men. Global warming is a religion, nothing more.
And did he incorporate the effect CFCs had on ozone levels? ” A 2013 study suggests that the ban on ozone depleting chemicals may have also impacted the rise in global temperatures. CFC gases were responsible for a massive hole in the ozone layer but they also had a powerful greenhouse effect. The authors link a ban on their use to a “pause” or slowdown in temperature increases since the mid 1990s. The research is published in the journal Nature Geoscience. The subject of a hiatus or standstill in global temperatures rises since 1998 has been the subject of intense… Read more »
“Climate Change leaves us with, basically, two ways out. One is extraordinary technology: either a silver bullet to produce cheap, renewable energy, or a reliable geo-engineering technique to adjust the global …weather system directly. Either might happen—the first likely will, maybe too late to prevent permanent crisis; but waiting on clean energy is a very big risk, and geo-engineering brings huge risks of its own …ending up making the system even more unstable.” Jedediah Purdy Climate Change Needs the Politics of the Impossible U.S. News April 6, 2014 A cheap green silver bullet, the missing, singularly realistic, path to slowing… Read more »
No matter what, this entirely IGNORES whatever caused the huge fluctuations in the past, before man built a factory, drove a car, or even built a fire.
no way, no how, is man going to ruin this planet in this way, and the SCARE TACTICS like this (so that governments can demand money and power) is despicable.
so, why is it that the human infestation of the planet is NOT considered a natural phenomenon ? … and therefore a natural cause for all kinds of conditions and events? More basic than that, maybe it was the primordial ooze that was the original pollutant of the planet.
There are two sides to every story, but when it comes to climate change, only one of those sides has even a shred of credibility, since 80-90 percent of credible scientific research points to the reality of human-caused climate change. Of course oil and gas industry propagandists, and their useful idiots in the right-wing media, have spent billions of dollars and countless hours putting forth a propaganda line to marginalize the science, much as Dubya Bush had information redacted if it didn’t please his oil and gas industry overlords. And people buy it – after all, this is a nation… Read more »
Who would have guessed the answer was so obvious? Or is it…
“Lovejoy’s analysis uses carbon-dioxide from the burning of fossil fuels as a proxy for all man-made climate influence”
Seeing as CO2 levels rise in response to temperature increases (not as a result of), as shown in ice core data, this study is without merit and a waste of time.
Climate change is happening, but as far as it being man-made, I have my doubts…
This planet has always and will always be inhospitable… it is those who adapt that survive. If you want to stop global warming… stop having kids. Until you address that… I don’t want to hear about how you don’t like my car emissions.
So the medieval warm period was caused by humans also before fossil fuels? What about the little ice age? Theres been one average temperature for the last 10,000 years? 99% certainty huh?
Couldn’t care less about “Global Warming.”
Hmmm… So he set the arbitrary date at 1500? Oh yeah, that’s because when “mankind” started to expand its horizons and make things in a capitalist fashion? So, last time I was in Pompeii, the tour guide indicated to us that the gates to the city were actually 100 meters from the docks and Mediterranean Sea that the ships birthed at. Now, 3000 years later the water is not visible from those stone gates and in fact is over a kilometer away and quite a bit lower in elevation. Hmmm, what caused that??? Global unwarming? All I’m saying is that… Read more »
Actually, if you accept the line of reasoning in this paper and factor in the absence of warming in recent years, you could reasonably conclude that the warming was due to CFCs, not CO2. Personally I think that meta-studies like this are a poor substitute for hard science and are not to be trusted very far.
Let’s see. You are basing your analysis for a period from 1880 forward? Lead into the article says since 1500, before climate data was consistently kept….Boy am I confused. Has your information even been pier reviewed by the people that would agree with you as well as the MYRIAD of real scientist who seem to find different results. I would be VERY skeptical of making some grand proclamation like this except you really don’t care if it is factual, just so you can say it to retain your funding!!
These climate romantics never cease to amaze. Some call them alarmist, but I don’t. They are just very passionate individuals that need some sort of emotional fulfillment in their lives. It must have been very disheartening when one of their prophets James Lovelock recanted his global warming views in spring of 2013.
My grandfather had it right,’give a fool an education and you end up with an educated fool.’When you can explain how earth got rid of the last ice age without warming up then I will believe you.The idea that anyone would trust the
“Odds are” so calculating odds and calling it fact or evidence is now science? “Slim to none” is now what sort of scale? This is the problem with every argument the CO2 only, Human only global warming theory, you have no actual evidence. Flawed computer models are not evidence. The real planet earth’s atmosphere NOT behaving like the fake planet earth in the computer model is not evidence. Cherry picking data from 100+ years ago is not proof. Inventing meaningless values like “average global temperature” and then declaring a value which supports you theory is not evidence. Add to the… Read more »
My grandfather had it right,’give a fool an education and you end up with an educated fool.’When you can explain how earth got rid of the last ice age without warming up then I will believe you.The idea that anyone would trust the UN or anyone associated with it is an insult to common sense.Hell,if it wasn’t for nbc,cbs,and cnn I would have thought it got damn cold this past winter.Good luck in explaining to the citizens of Atlanta that all that ice and snow was really heatwaves laying on Atlanta. There is one chance in ninetynine that anyone associated… Read more »
It is very easy to make assertions of this type when you are intentionally limiting your viewpoint, and refusing to look at the larger picture:
“Global Warming” – The Lies Begin to Crumble – Part I
1500 the start of the minnie ice age that ended in the 1860s
Of course it going to warm up.
So, when do we start “eliminating” about 5 Billion Humans?
This article is ludicrous. It makes your entire publication look ludicrous.
Hey, guys, ever hear of something called “The Sun”? It provides all the warming the Earth ever gets, and it is completely a natural factor.
Too bad the computer models have not been coming true. Otherwise I might actually have to take notice of studies such as this. Good luck with that.
Didn’t a similar AGW theory lead to human sacrifice in the Aztec Empire?
A study of the varying sun cycles and its’ effects on earth over several thousand years.
Last time I looked humans were still natural. So, whatever we do is natural, duh. Just more species hate speech.
Statistician Matthew Briggs is only among the first of many who will blow holes through this document, and we can all hope Lovejoy sinks fast. (The publication of this study is prima facie that the purpose of true peer-review is dead.
“While the statistical rejection of a hypothesis can’t generally be used to conclude the truth of any specific alternative, in many cases – including this one – the rejection of one greatly enhances the credibility of the other.” In Response I would like to add my two cents and give the global warming community something more to research instead of jumping to premature conclusions. First of all, there has been no scientific proof that the co2 or any gas has actually warmed up the planet. As a matter of fact, Extensive research has proven that the gases on earth do… Read more »
I was told in school during the 70s that we were heading for a mini ice age. The older I get the more I realize how little science knows with any accuracy. No one can truly understand the power of the planet. The sun alone could fry all your educated guesses. The planet could spit us out tomorrow. This is not to say that we shouldn’t be responsible stewards. Too much consumption and population. Too much disposable waste society in general.
Not sure why people find it so hard to beleive that Humans can have such a large effect on the Earth. Nor do I understand why the deniers take it personally, as if they were being scolded by their parents in front of their friends. Among my more scientific-minded, academic-savy friends, I find little doubt that Humans could so greatly affect the Earth’s Climate, if not inevitably. I really only find climate change deniers among my religious fundamentalist friends and the handful that get all of their education from fox news pundits. I would even go as far as to… Read more »
I’m looking for funding to write a scientific study proving that extensive breathing causes increased levels of co2 and , hence, the global warming. If the humans can decrease the rate of breathing by 20%, the global temperatures will drop by 2C by 2050.
Ok, lets assume that man made global warming is 100% real. The only way to “turn off” CO2 production is for humans to stop using carbon based fuels. Exactly how would this be accomplished? The current global population and modern society as we know it would collapse if we stopped using fossil fuels today. Half the world’s population would die within 5 years due to starvation! The collective population of Earth is not going to plunge it’s self back into the stone age to “save the planet”. Not gonna happen! Why are we arguing about the warming? We should instead… Read more »
They must have had some big coal fired power plants before the Medieval Warm Period.
Without questioning the assumptions made, in order to generate the data, or the analysis(which would presumably be defended in the article), we still can’t quantify the man made contribution to warming, nor ACCURATELY predict how we can adjust global warming with our activity, or IF we should. We know the earth has warmed steadily since the last ice age, but we can’t say to what degree man made activity has altered it. Since warming is a natural cycle, who says mankind should interfere to alter it? We seem overly obsessed by the impact warming would have on OUR species, and… Read more »
In order to prove that CO2 raises temperature, lets do a study using CO2 as a proxy for temperature. Yeah, that’s the ticket.
I wonder if the same proxies and reconstructions that were used to create Michael Mann’s famed and widely debunked Hockey Stick were used in this “study.” It appears that the global warming alarmist crowd are getting more and more desperate to allow for globalist control and taxation of their lives. Just look at the lead-off to this article: “This study will be a blow to any remaining climate-change deniers,” Lovejoy says. “Their two most convincing arguments – that the warming is natural in origin, and that the computer models are wrong – are either directly contradicted by this analysis, or… Read more »
Sad to read these comments, willful ignorance,
Gives licence for greed and selfish hubris, the information is available, that shows the massive amout of data which points to man made warming. Deniers are willfully ignorant or twisting the data… Instead of caution they promote greed , hubris and selfishness!!!
We have clean energy, have had it for nearly 70 years now. That the Greens reject it because it gives you all waste in a controllable lump is the insanity of the Greens, not anything to do with physics. Thorium based nuclear power using molten salt reactors is the safest and cleanest power known to man, including solar and hydro and wind. It’s so much safer than any fossil fuel that it’s not worth mentioning. The usual “green” aka idiot argument against nuclear goes “but it skeers me cause bombs”. Building bombs from thorium is nearly impossible, it would likely… Read more »
A physicist conducting a global warming study is like a Boeing 747 captain conducting a study involving a helicopter. Yes, Lovejoy is a scientist, but he is not an expert in the field of climatology.
Hydrogen energy now! It’s been doable for a hundred years — and it’s rather carbon neutral when the electrolysis of water (to separate hydrogen from oxygen atoms) is done with wind and solar energy.
(Here’s where the dumb people and Big Oil defenders start calling hydrogen a complicated technology that we’re not ready for.)
The ignorance in the comments here is indeed staggering. We are a country of idiots, and I weep for the future.
After 4 billion years of climate change? Why would you EVER think it could be controlled?
I’m not terribly bright but, thanks to all of the climate “experts” commenting on this article, I think I’m a little more stupid than I was before reading them. Thank goodness we have such bright and capable laypeople to prevent us from being duped by all of those evil scientists with their fancy degrees. You know: the ones who actually do field work and spend time in laboratories and analyze the growing wealth of available data and evidence.
Methane Gas And Clathrate Ice Melting Trends Accelerating, Multiple Tipping Points Breached; via @AGreenRoad
Top 100 Global Warming Denialist Groups Are ALL Funded By HUGE Corporations; via @AGreenRoad
Nuclear Energy As A Direct Cause Of Global Warming; via @AGreenRoad
MaineUKFan – try listening to the scientists whose jobs don’t depend on the outcome. There are plenty out there screaming to be heard. You just have to listen to them. Do you think someone who has received a big research grant to study antrhopogenic global warming is likely to conclude that there’s no basis for it?
Hi, I am not a scientist though I am well versed in Physics and Chemistry. They are not my profession more a passion that drove me to do graduate level coursework in both areas. With that in mind, I have a question that I would like you to address if you will please. I am not one of these “anti-global warming” conspiracists, but with any real science work, healthy skepticism is the foundation of the long term viability of any theory. I have heard the debate from several sides of the “man-made” global warming question but what really stands out… Read more »
Eric, the more you look, the more problems like this you find. For example, the recent wave of warming started in about 1910 – well before human emissions became significant. Temperature increased for about 30 years, then stopped for 30 years, and increased again at the same rate as the original rise. So what caused the initial increase, if it wasn’t human emissions, and what makes us think that 1970 – 2000 was any different?